1. Technical Field
The invention is related to helical scan tape cassette recorders such as video cassette recorders. The invention is also related to mass memories for computers. Mass memories typically store very large amounts of data (on the order of 10.sup.10 bits) and typically are realized as large and expensive tape storage systems, magnetic core systems or large disk drive systems.
2. Description of the Related Art
Mass Memories
Mass memories are an essential feature of the latest generation of very powerful high speed computers. Such a computer retrieves a block of data from the mass memory and stores it in a buffer memory for ready access to small or selected portions of the block of data. Whether realized in the form of magnetic cores, magnetic tape or disk systems or very large scale integrated circuits, mass memories suffer from being either bulky or expensive, or both. For example, it would require about one thousand 31/2 inch floppy disks to furnish the 10.sup.10 bit-capacity of a mass memory.
Video Cassette Recorders
In order to achieve high information density in magnetic tape recording of color video signals, a video cassette recorder (VCR) employs helical-scan recording techniques to record video signals at relatively slow tape speeds. For example, an 8 mm video cassette can record two hours of a video program. The problem is that accessing a particular portion or program recorded somewhere in the middle of the video tape length is time-consuming and may require several attempts before the tape is exactly positioned at the desired location. Thus, VCR's are not suitable for applications requiring quick access to small blocks of video programs or recorded information.